The evolution of insecticide resistance by insects will be simulated on a computer. The objects are: (1) to better understand why insecticide resistance has evolved rapidly in some circumstances but not in others; and (2) to use this information in developing control strategies, whereby insect population densities are kept low but resistance does not evolve. We have already achieved some progress toward both objectives. By means of simple models we have shown that dominance of alleles which confer resistance, migration rates, and initial population size and gene frequency are important factors in the evolution of resistance. We have also shown that by properly adjusting these parameters through manipulation of insecticide dosage and introduction of susceptible individals, simulated populations may be prevented from evolving resistance. We will develop this method of control in more detail. The proposed studies will concentrate on modelling more complex life cycles and determining how polygenic resistance, cross resistanc, and insectcide persistance might affect this evolution. The simulations are preparatory to initiating population cage experiments.